Therapies have been developed for treating atrial and ventricular tachycardias by destroying cardiac tissue containing an identified ectopic foci or an aberrant conduction pathway; one of these therapies includes the application of ablative RF energy delivered through a catheter, which may be introduced transvenously into the heart, via a catheter electrode in direct contact with the arrhythmogenic site of the cardiac tissue. Because of the nature of RF energy, both the electrode contacting the tissue and the tissue are heated simultaneously; the amount of tissue heating that occurs is dependent upon the area of contact between the electrode and the tissue and the impedance between the electrode and the tissue, the lower the impedance the greater the tissue heating. An electrode that is actively cooled by an irrigating fluid is more efficient in the transmission of ablative energy into the tissue and reduces the potential for complications arising from an excessive electrode temperature (approximately greater than 100 degrees Celsius) that may cause formation of blood coagulum and sub-surface explosions or pops within the tissue.
Physicians have long used the technique of pressing against the endocardium an ablation element mounted on a distal end of a catheter, applying ablation energy, and dragging the electrode along the endocardium to create an elongated lesion. Consequently, there remains a need for an improved ablation catheter including an irrigated tip electrode that is simple to fabricate and to use efficaciously in this manner.